How the EV break-even calculation works
AutoPrisme converts petrol and electricity consumption into a cost per kilometre. The annual energy difference is combined with the maintenance saving you enter. That annual advantage is then compared with the EV purchase premium after the estimated resale advantage.
Net EV premium = purchase premium − resale-value advantage.
The mileage threshold answers a different question: how far would you need to drive each year for the annual savings to recover that premium within the selected period?
Use a realistic blended charging price
Home charging can be much cheaper than frequent rapid public charging. If 80% of your energy comes from home and 20% from a public charger, weight both prices instead of entering the cheapest tariff for every kWh.
| Input | Why it matters |
|---|---|
| Annual mileage | More distance multiplies the per-kilometre energy difference. |
| Charging mix | Rapid public charging can reduce or remove the energy advantage. |
| Purchase premium | A larger initial gap takes longer to recover. |
| Ownership period | More years allow annual savings to accumulate. |
Worked example at 15,000 km per year
The default example compares 6.8 L/100 km at 1.80 per litre with 18 kWh/100 km at 0.30 per kWh. It then tests a 6,000 EV premium, a 250 annual maintenance saving and a 1,500 resale advantage over five years. These are teaching inputs, not current market averages: replace every value with local data.
Frequently asked questions
What electricity price should I enter?
Use the average price you genuinely expect to pay. If you combine home, workplace and rapid public charging, calculate a blended price per kWh.
Does the calculator include grants or tax credits?
No. Enter the EV purchase-price premium after any confirmed incentive you are entitled to receive. Rules differ by country and can change.
Why include an estimated maintenance saving?
Energy is not the only difference. The field lets you test a cautious annual maintenance advantage, but you can enter zero if you prefer not to assume one.
Is a lower running cost enough to justify the EV?
Not necessarily. Charging access, insurance, range, depreciation, finance and how long you keep the car can be more important than energy cost alone.